# Tagged Questions

Fiter design is the process of designing a filter.

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### Low-pass elliptic filter design: equation for calculating required minimum order

In this paper on page 4 (or in slide page, 23), it describes the equation for calculating the minimum required order for elliptic filter for design specification. However, it says it is only the ...
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### Anti tremor motion detection

I'm programming in c# using opencv (emguCV). I use motion detection approach to detect some changes in a paper wall. For example it's may be colored by a laser pointer. My problem is that when I use ...
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### Designing bandpass FIR filter MATLAB

I am trying to design a FIR bandpass filter for a STM32F407 microcontroller with a passband of 1kHz between 59500 Hz and 60500 Hz or something similar (since I don't really know how tight I can ...
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### Why is a linear phase important?

If symmetry conditions are met, FIR filters have a linear phase. This is not true for IIR filters. However, for what applications is it bad to apply filters that do not have this property and what ...
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### How to construct a preemptive digital filter to neutralize an unwanted filter

I'm trying to think of how to construct a filter based on the following scenario. I have some time trace with a certain known power spectral density (I can verify this with a periodogram of the time ...
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### Analytically Deriving butterworth Filter [closed]

I am pretty new to Digital Signal processing, I did my back end research, but I was overwhelmed by the variety of the solutions I got. I want to Analytically derive a Butterworth filter with only "...
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### Decomposition of $H(z)$ as maximum-phase, minimum-phase

The frequency response is: $$H(z) = 2-7z^{-1}+7z^{-2}-2z^{-3}$$ I see that it has $3$ zeros: $z_{01} = \frac 12$, $z_{02} = 2$, and $z_{03} = 1$; and $3$ poles in: $$z_x = 0$$ Now, I have to write ...
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### Maximum phase with the same magnitude response

I'm trying to solve an exercise in a general way and I can't find if my answer is correct. Given this frequency response: $$H(z) = 4 + 2\sqrt2 z^{-1} + z^{-2}$$ I need to find a frequency response ...
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### Testing filter code w/ Octave

I want to test some code generated by this site. I selected Bessel LP 1st sample rate $600\textrm{ Hz}$ corner $8\textrm{ Hz}$ long $10\textrm{ bit}$. If I adjust the code for octave to be: ...
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### Weighting function for output error IIR filter design

I noticed, when I try to fit filter coefficients to a given complex transfer function with the output error method, implemented for example in the MATLAB function ...
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### How many types of Bandpass filters are there for image processing?

This article shows that: Ideal Bandpass filter Butterworth Bandpass filter Gaussian Bandpass filter Is that classification correct? Are there any other types?
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### What is Local Mean Filter?

The research paper "Multidirectional Scratch Detection and Restoration in Digitized Old Images" says that, 4.1. Preprocessing. The preprocessing step aims to enhance image features along a set of ...
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### What is a filter bank?

I have three Gabor filters. I am applying them to an image serially. Is this the correct concept of a Filter Bank? What if I want to apply the filter in parallel? I am using Accord.NET framework. ...
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### Upsampling with FIR filter causing discontinuity at start of new buffer [closed]

I have implemented an oversampling algorithm for an audio signal in C++ which is producing a distortion of the signal at the start of a buffer. The algorithm is wrapped in a class with methods for up ...
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### Basic tools for digital filter design?

What tools to use for practicing elementary filter design? Is MATLAB all there is? Do I need some specific toolboxes? What functions do I need? I'm starting from the ground up in digital filter ...
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### How many taps does an FIR filter need?

I am looking to design a set of FIR filters to implement a low pass filter. I am also trying to reduce the latency of the signal through the filter so I am wondering what the minimum number of taps I ...
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### What is the multi-resolution analysis form of Gabor filter?

The multi-resolution analysis form of Gabor filter is as follows: \begin{align} \psi\left(x,y;f_0,\theta\right)&=\frac{f_0^2}{\pi\gamma\eta}\exp\left[-\left(\frac{f_0^2}{\gamma^2}x'^2+\frac{f_0^2}...
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### When should we use the full Gabor Function and when do we use only the real part?

In this YouTube video, we see that the guy is only using the real part of the Gabor Filter to implement his project. My questions are, When should we use the complex Gabor Function? When should we ...
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### Deriving the multi-resolution analysis form of Gabor filter from the standard form

The standard form of a 2D Gabor filter is as follows: \begin{align} g_{\lambda, \theta,\varphi, \sigma,\gamma}(x, y)&=\exp\left(-\frac{x^2+\gamma^2y^2}{2\sigma^2}\right)\cos\left(2\pi\frac{x'}{\...
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### Goodness of fit for complex valued curves (i.e. frequency responses in frequency domain)

My apologies for perhaps the stupidity of this question. Presume that one has the 'frequency response' $Y_{data}(k)$ of a system and also has an estimated model $Y_{syn}(k)$ that fits the data. How ...
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### anti aliasing filter which suppresses spectral components above half sampling frequency

I'm new to designing filters, and I have to make an anti aliassing filter (in python) in function of the subsampling factor, which suppresses spectral components above half the sampling frequency with ...
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### Lowpass Butterworth filter design (own poles' calculations)

I'm trying to calculate coefficients for my Butterworth filter of my own. I've found this article that looks really reliable. But I'm trying to implement it in MATLAB and I'm getting bandstop filter. ...
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### Hilbert FIR Filter for Q - Matching Filter for I

For an ultrasound application, I am collecting data from an ADC using high spec Altera FPGA which grabs data and can then do some DSP processing that would be otherwise too slow for a desktop to do. ...
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### How are these pole zero plots created

Back around 5 BC, where C stands for the programming language, engineers would photograph their oscilloscope's display to record their test results. This appears to be such a photograph, taken from ...
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### Stopband Attenuation

Why is a stopband attenuation of -40dB preferred for the filter design & analysis. I understand at this magnitude response point, the o/p is just 0.01 of the O/P but how does it help in defining ...
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### Can we determine if a filter is butterworth or chebyshev from its physical topology?

Can all analog filters be classified as Bessel, Elliptic, Butterworth or Chebyshev? Given a physical ladder topology of several stages of {L, C or LC} in {series or parallel}, is it possible to ...
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### How can a signal have two maximum frequency components?

$x(t)$ can be exactly reconstructed from its samples at $\omega_s = 10 \textrm{ rad/sec}$. My conclusion is that the maximum frequency component in $x(t)$ is $5\textrm{ rad/sec}$. But I'm being told ...
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### Analytical way to generate an IIR that is the square root response of another IIR

For simplicity take the transfer function of a second order IIR in $z$-domain: $$H(z) = \frac {b_0 + b_1 z^{-1} + b_2 z^{-2}} {a_0 + a_1 z^{-1} + a_2 z^{-2}}$$ Is it possible to generate a new ...
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### describing a block diagram // How do I describe multiplying a signal through multiple branches formally?

Let's say I made this block diagram and I want to explain it: FYI: $x$ is a signal and each $y$ box is a matrix I want to say that: The signal $x$ is multiplied by each matrix $y$ in the ...
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### What is the difference between a'mixer' and a ' multiplier' used in modulation process?

I am not sure if it is valid to conclude that a mixer produces a difference/sum of frequencies at output ,while multiplier produces multiples of frequency at its output. I am keen to know how far I ...
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### How to design Bi orthogonal wavelet filter bank

I know in orthogonal wavelet system analysis filters can be made by flipping the synthesis filters(vice versa) but in bi orthogonal system this will not work because the co efficient are symmetric in ...
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### Can two different impulse responses give the same frequency response?

I have two different impulse response each with different length, is it possible that they have the same frequency response?
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### Real digital filter property

I am a beginner to study about the filter notion and property Being a real digital filter, (here "real filter" I means that its impulse response is real-valued) this formula is established. But I ...
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### s_to_z (Pupalaikis)

Paper: Bilinear Transformation Made Easy - http://documents.mx/documents/easybilinearpdf.html Example of implementation - http://codepad.org/u3tvKn0S I get the same output for Butterworth lp example ...